Here is a puzzle: □ + 5 = 12. The box is hiding a number. What number do you think is hiding in the box to make both sides equal?

Watch the balance beam. A box hides a number, and the beam only stays level when the box holds the right value. To find the box, we do the opposite of what is beside it. Whisper your prediction for each beam, then check that it is level.

We start on the balance beam with □ + 4 = 11. Set the box until the beam levels, then read off what the box holds. Then we talk through the next ones together: □ − 2 = 6, then 8 = □ + 3, then 10 + □ = 17.

First we walk one new shape together on the board: □ + □ = 16. Both boxes match, so we halve the total to find one box, then put 8 back in to check. After that it is your turn on the beam. Set the box, press Check, and we confirm each one before moving on. First is □ + 6 = 14. Then comes 20 = 13 + □, where the box fills the gap. Next is the twin-box one, □ + □ = 16. Last is □ + 7 = 5 + 9, so work out the far side first, then find the box.